1. Field of the Invention.
The present invention relates, generally, to an apparatus and method and for controlling exhaust emissions, and is particularly suited for controlling unburned diesel particle emissions from a diesel engine.
2. Background Information.
A great deal of effort has been spent attempting to control emissions of diesel engines. U.S. pat. No. 5,987,882 to Voss et al. contains a thorough background discussion on diesel emissions and numerous references related to the well known subject, which will not be reiterated here.
Among other unwanted emissions, unburned carbon particles are typically present in exhaust from diesel engines. The unburned particles are particularly troublesome because carcinogenic materials are attached to the carbon particles as a product of the diesel combustion process. The carbon particles with the carcinogenic materials attached, often called "diesel particles", are usually in the form of sub-micron to micron sized particles which can be inhaled, thereby depositing the carcinogenic materials into people's lungs.
In the past, these particles have been trapped by a particle trap then burned using an additional burner, such as disclosed in U.S. Pat. No. 4,881,959 to Kono et al. Such burners are relatively inefficient in heating the diesel particles to a sufficient temperature to oxidize.
Applicant's invention provides an improved diesel particle oxidizer which efficiently heats the diesel particles using visible light energy. The applicant's invention may also be applied to any carbon particles in an exhaust stream from any combustion source.